Audio playback timing is inconsistent
So I was able to get the video edited without any problems this time. Turns out my original issue was indeed the Sync Mode setting, which needed to be in AV Sync for the audio playback timing to work. The later issue was also causes by the Rendering options being set to the wrong FPS. It was set to 30 fps when the files I was importing were recorded in 15 fps. Once I got those sorted out everything worked and I was able to create and upload the video with no further problems. Thanks for your help @bertmoog.